Dr. Dwight B. Waldo, first president of Western Michigan University in Kalamazoo, Michigan
"Edward Hamilton Waldo" was the birth name of American science fiction author Theodore Sturgeon (1918-1985), who legally changed his name in 1929.
John B. Waldo (1844-1907), jurist and conservationist in Oregon of the United States
Peter Waldo, (1140 - 1218), founder of a Christian sect called the Waldenses
Rhinelander Waldo (1877-1927), a former U.S. Army Captain who served as the Fire and later the Police Commissioner of New York City in the early to mid 1910's.